3 DIFFERENT SYSTEMS OF MONOAMINE-STORING CELLS IN GASTROINTESTINAL TRACT OF FETAL AND NEONATAL RATS

The development of three monoamine‐storing cell systems in the wall of the duodenum, glandular portion of stomach, and ileum has been followed histochemically in fetal and newborn rats, and compared with the number and characteristics of such cells in adults. 5‐Hydroxy‐tryptamine can be demonstrated in mast cells and enterochromaffin cells already a few days before birth. Part of the mast cell population, i.e. the one which in adult animals is found as “atypical” mast cells near the mucosal surface, is able to take up high amounts of L‐DOPA. “Enterochromaffin‐like” cells, exclusively found in the oxyntic gland area of the gastric mucosa, are also able to take up and, probably decarboxylate, L‐DOPA already at birth. Their number increases progressively in the following stages. Gastric DOPA decarboxylase activity is high already at a stage when the capacity to store monoamines has not yet developed in the enterochromaffin‐like cells, the system of monoamine cells quantitatively dominating in the stomach wall. The finding suggests that DOPA decarboxylase occurs also in other cell systems, such as mast cells and enterochromaffin cells, which are capable of storing monoamines earlier than the enterochromaffin‐like cells. The activity of gastrointestinal DOPA decarboxylase reaches adult levels already by the time of birth, and is probably primarily associated with the two systems of enterochromaffin and enterochromaffin‐like cells. © 1969 Scandinavian Physiological Society